In our topology R1 and R3 are VPN peers, having PC1 and PC2 as end client which are going to communicate with each other using secure tunnel and R2 is the router, routing only public IP address.

 

Before VPN configuration we have made the VPN peers reachable to each other and DIGITAL CERTIFICATE has been enrolled by peers.

 

We are using

AES for encryption algorithm (for IKE phase 1 and IKE phase 2)

SHA as hashing algorithm (for IKE phase 1 and IKE phase 2)

Diffie-Hellman group 5

Name of the transform-set used CISCO-SET

Name of crypto map used CISCO-MAP

 

CONFIGURATION OF VPN AS FOLLOWS

On R1 in global configuration mode

 

 

R1(config)#crypto isakmp policy 1

R1(config-isakmp)#authentication rsa-sig

R1(config-isakmp)#encryption aes

R1(config-isakmp)#hash sha

R1(config-isakmp)#lifetime 1800

R1(config-isakmp)#group 5

R1(config-isakmp)#exit

R1(config)#crypto ipsec transform-set CISCO-SET esp-aes esp-sha-hmac

R1(cfg-crypto-trans)#mode tunnel

R1(cfg-crypto-trans)#exit

R1(config)#crypto ipsec security-association lifetime seconds 1800

R1(config)#ip access-list extended 101

R1(config-ext-nacl)#permit ip 192.168.101.0 0.0.0.255 192.168.102.0 0.0.0.255

R1(config-ext-nacl)#exit

R1(config)#crypto map CISCO-MAP 10 ipsec-isakmp

R1(config-crypto-map)#set transform-set CISCO-SET

R1(config-crypto-map)#set peer 102.1.1.100

R1(config-crypto-map)#match address 101

R1(config-crypto-map)#exit

R1(config)#int f0/1

R1(config-if)#crypto map test

 

On R3 in global configuration mode

 

R1(config)#crypto isakmp policy 1

R1(config-isakmp)#authentication rsa-sig

R1(config-isakmp)#encryption aes

R1(config-isakmp)#hash sha

R1(config-isakmp)#lifetime 1800

R1(config-isakmp)#group 5

R1(config-isakmp)#exit

R1(config)#crypto ipsec transform-set CISCO-SET esp-aes esp-sha-hmac

R1(cfg-crypto-trans)#mode tunnel

R1(cfg-crypto-trans)#exit

R1(config)#crypto ipsec security-association lifetime seconds 1800

R1(config)#ip access-list extended 102

R1(config-ext-nacl)#permit ip 192.168.102.0 0.0.0.255 192.168.101.0 0.0.0.255

R1(config-ext-nacl)#exit

R1(config)#crypto map CISCO-MAP 10 ipsec-isakmp

R1(config-crypto-map)#set transform-set CISCO-SET

R1(config-crypto-map)#set peer 101.1.1.100

R1(config-crypto-map)#match address 102

R1(config-crypto-map)#exit

R1(config)#int f0/1

R1(config-if)#crypto map test

 

I hope it solves your query. Its a basic practical and part of CCNP Security Certification syllabus. If you want to learn more about VPN technologies, you can prepare for CCNP Security and CCIE Security Certifications through some training institute or by self study.

thanks